MFC r316579

MFC r316579

 makefs: use emalloc and friends

 The emalloc set of error-checking memory allocation routines were added
 to libnetbsd in r316572. Use them in makefs to reduce differences with
 NetBSD.

 NetBSD revs:
 cd9660.c			1.39
 ffs.c				1.56
 makefs.c			1.42
 walk.c				1.27
 cd9660/cd9660_archimedes.c	1.2
 cd9660/cd9660_eltorito.c	1.20
 cd9660/cd9660_write.c		1.16
 cd9660/iso9660_rrip.c		1.12
 ffs/buf.c			1.17
 ffs/mkfs.c			1.26

Sponsored by:	iXsystems, Inc.